Deep brain stimulation is considered for essential tremor when tremor interferes with eating, writing, dressing or work, and medication has failed or cannot be tolerated. Stimulation is delivered to the ventral intermediate nucleus (VIM) of the thalamus, the posterior subthalamic area (PSA), or both. Most patients regain the ability to hold a cup, eat unaided and write legibly; tremor control is generally immediate once stimulation is optimised.
At a glance
- Usual targets
- VIM thalamus; posterior subthalamic area / caudal zona incerta (PSA/cZi)
- Double-target option
- One electrode trajectory passing through both VIM and PSA — described by Prof. YILMAZ and colleagues, Stereotact Funct Neurosurg 2024
- Typical candidate
- Disabling action tremor; inadequate response to, or intolerance of, medication; good cognition
- One or both sides
- Both sides in most patients; staged or bilateral depending on symptoms and speech risk
- Onset of benefit
- Immediate with stimulation, refined over following weeks
- Main trade-off
- Speech changes and balance effects, particularly with bilateral thalamic stimulation
Essential tremor is not Parkinson's disease
The two are frequently confused, including by clinicians. Essential tremor is an action tremor — it appears when the hand is doing something: reaching for a glass, bringing a spoon to the mouth, signing a name. Parkinsonian tremor is typically a rest tremor that settles when the hand is used. Essential tremor is usually symmetrical, often familial, frequently involves the head or voice, and does not cause the slowness and rigidity of Parkinson's disease.
The distinction matters because the surgical target differs. Getting the diagnosis right is part of candidacy assessment, not a formality.
Who benefits
- Tremor severe enough to interfere with daily function — eating, drinking, writing, using tools or a keyboard, or work that requires steady hands.
- Medication has been genuinely tried at adequate dose and either has not worked or cannot be tolerated.
- Cognition is intact and expectations are realistic.
- No untreated severe depression, no active infection, no uncontrolled bleeding risk.
VIM, PSA, or both
The VIM nucleus of the thalamus has been the standard tremor target since the 1990s and controls tremor well in most patients. Two problems appear over time in a minority: tremor returns despite increasing stimulation (habituation), and bilateral thalamic stimulation can affect speech and balance.
The posterior subthalamic area, including the caudal zona incerta, produces tremor control with a different side-effect profile and often at lower stimulation amplitudes. Prof. YILMAZ trained with Prof. Patric Blomstedt in Umeå, whose group established this target.
Double targeting: VIM and PSA through one electrode
This is the technique Prof. YILMAZ and colleagues described and published. A single electrode is placed along a trajectory that passes through both the VIM and the posterior subthalamic area, so that different contacts on the same lead reach different targets. During programming, stimulation can then be balanced between the two — more thalamic, more subthalamic, or a combination — and rebalanced later if the tremor changes or if speech side effects appear.
For a patient with essential tremor this matters in three ways. It gives the programmer two distinct circuits to work with instead of one, which counts when tremor control and speech pull in opposite directions. It offers a route to recover control in patients whose response to VIM stimulation fades over the years. And it achieves this without a second brain pass, so it does not add the haemorrhage risk that an additional trajectory carries.
Peer-reviewed publicationDeep Brain Stimulation with Double Targeting of the VIM and PSA for the Treatment of Rare Tremor SyndromesYilmaz A, Eray HA, Çakır M, Ceylan M, Blomstedt P. Stereotactic and Functional Neurosurgery, 2024 · doi:10.1159/000539162 · PubMed 38934181Focused ultrasound, radiofrequency lesioning or DBS?
| DBS | Lesioning (RF or focused ultrasound) | |
|---|---|---|
| Reversible | Yes — stimulation can be adjusted or switched off | No — the lesion is permanent |
| Adjustable over time | Yes, as tremor changes | No |
| Both sides | Standard, with appropriate caution | Bilateral lesioning carries higher speech and balance risk |
| Implanted hardware | Yes — electrodes and a generator, battery replacement needed | No hardware |
| Best suited to | Bilateral tremor; younger patients; tremor likely to progress | Strictly one-sided tremor; patients who cannot accept an implant |
What to expect afterwards
Tremor control is usually apparent as soon as stimulation is optimised, which is one of the most striking things about this operation. Programming is then refined over the following weeks. Speech changes — softer or slightly slurred speech — are the most common stimulation side effect with thalamic stimulation and are usually manageable by adjusting settings, sometimes at the cost of a little tremor control. Some patients experience gradual loss of effect over years, which can often be recovered by reprogramming.
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Frequently asked questions
Does DBS cure essential tremor?
No. It controls tremor while the stimulation is on. The underlying condition continues, and if the device is switched off or the battery depletes, tremor returns.
Will both hands be treated?
Most patients with bilateral disabling tremor have both sides treated. Whether this is done in one operation or in two stages depends on the individual, particularly on speech and balance risk.
What is the difference between VIM DBS and PSA DBS for tremor?
VIM is the classical thalamic tremor target. The posterior subthalamic area (PSA), including the caudal zona incerta, lies below and behind it, often controls tremor at lower stimulation amplitudes, and can work in patients whose tremor responds incompletely to VIM stimulation. A double-target approach stimulates both through one electrode.
Can tremor come back after DBS?
It can. Some patients lose effect gradually over years — habituation. Reprogramming, using different contacts, or shifting stimulation towards a second target often restores control.